This invention relates to a column adapted for high pressure liquid chromatography of the type having a glass column adapted to be filled with the sorbent and which is surrounded concentrically, with an intermediate space being maintained therebetween, by a pressure tube.
Such columns are known, for example, from German Utility Model No. 7,146,039, German Offenlegungsschrift No. 2,329,286 and German Auslegeschrift No. 2,524,751. In these known columns, the intermediate space between the glass column and the pressure tube is filled with the eluent, as the pressure liquid, used for the chromatographic separation by connecting the intermediate space to the eluent feed, so that the pressure acting externally on the glass column is the same as or greater than that inside the column and the glass column thus cannot explode from the pressure of the eluent.
It has been proposed to seal off the intermediate space from the ends of the column so that the eluent contained in the intermediate space cannot mix with the eluent entering at the top of the column. In German Offenlegungsschrift No. 2,329,286, this is achieved by sealing off the ends of the column from the intermediate space with O-rings, which has the disadvantage that the glass column must be matched precisely to the length of the pressure tube, with minimum tolerance.
It is thus proposed in German Auslegeschrift No. 2,524,751 to seal off the glass column from the intermediate space with a seal of the stuffing box type, whereby even relatively large differences in length of the glass column can be tolerated. Polytetrafluoroethylene seals are used as the stuffing box-type seals. Although these seals are resistant towards the eluent present in the intermediate space, they have a relatively low elasticity, so that the diameter tolerances of the glass column to be compensated by the seals are small. These stuffing box-type circumferential seals also make it very difficult to change the glass column. More specifically, in order to change the column, the screws at both ends of the pressure tube must be undone and at least one of the two such seals, which have been pressed firmly onto the glass tube, must be removed so that the glass column can be pulled out of the pressure tube. A further disadvantage of this construction is that a free space must be provided between the end of the column and the screw connection of the pressure tube in order to compensate for length variations in the glass column. This means that the column is not firmly clamped in the longitudinal direction, so that leaks in the inflow and outflow capillaries, which necessarily fit in only relatively loosely, can very easily result.
It is an object of this invention to prove a column for high pressure liquid chromatography which uses simple head seals which permits easy change of the glass column and which permits the use of glass columns with relatively large variations both with respect to diameter and with respect to length, and in particular, which employs seals for the glass column which do not come into contact with the pressure fluid. Other objects will be apparent to those skilled in the art.